Steam superheating installation



Jan. 18, 1944. 4 J WO 2,339,444

STEAM SUPERHEATING INSTALLATIONS Filed June 12, 1942 INVEN TOR. JOHN 5.WOOD (0505 4550) BARCLAYS BAA/A LIMITED BY- 77mins 50/Vf/H'607'0fi)HTTOIP EY Patented Jan. 18, 1944 UNETED STATES PATENT OFFICE 2,339,444STEAM SUPERHEAT'ING INSTALLATION John Edwin Wood, deceased, lateofAltrincham,

England, by Barclays Bank Limited, executor, London, England, assignorto The superheater Company, New York, N

- Delaware Y., a corporation of 1 Claim.

This invention relates to steam superheating installations of the kindin which the superheating is carried out in stages, and the control ofthe final steam temperature is effected by desuperheating the steam, byinjecting water thereinto, between stages.

The present invention may extend to superheaters having more than twostages or passes, and known as multi-pass superheaters, or may beapplied to a two-stage superheating installation, i. e. an installationcomprising a primary section and a secondary or final section.

Where the water supplied for desuperheating the steam between thesuperheating stages is injected into the steam as it enters the inletheader of the secondary or finalsuperheater there is a liability of thewater being unequally distributed amongst the. elements of the saidsuperheater. This is undesirable, for, as will be appreciated, shouldsome elements receive a relatively large proportion of water, resultingin the temperature of the steam leaving these elements beingconsiderably below the -mean final steam temperature, other elementsreceiving less water must work at steam temperatures considerably abovethe said mean final temperature with the liability of excessive metaltemperature arising in such elements.

It is an object of the present invention to provide in a superheatinginstallation of the kind indicated an improved steam temperature controlapparatus of the intermediate water injection type from which thedisadvantages arising from unequal Water distribution amongst theelements of the respective section of the superheater concerned shall beabsent, the invention seeking to provide a controlled superheater inwhich the injected water will be evaporated and distributed in the steambefore the latter enters the elements of the secondary or other sectionof the superheater which immediately follows the water injection,without the provision of any external mixing device, such as anadditional drum or vessel or a relatively long length of steam pipe,between the outlet and inlet headers of the primary and secondarysuperheaters respectively, or the equivalent headers of two sections ofa multi-pass superheater. I

Steam temperature control apparatus has been proposed in which the waterrequired for desuperheating purposes between superheatin stages issprayed into the steam in the outlet header of a section of thesuperheater before the final section; according to the present inventionall the water injected for desuperheating purposes into the steam in anoutlet header of a section of the superheater preceding the finalsection is delivered thereinto at the end '01! such header remote fromits outlet end, whereby before entering the elements of the finalsection of the superheater all said water is caused to traverse in thesuperheater, with the steam, a relatively long distance constituted bythe length of such header, and to meet in the latter the streams ofsteam which issue thereinto from the elements connected thereto, andwhich set up in such header a state of turbulence effective tothoroughly mix the steam and water and ensure vaporisation of thelatter.

In carrying the invention into practice, the water, in the case of atwo-stage superheater, is injected into the outlet header of the primarysection of the superheater. Where a multistage superheater is concerned,all the water required may be injected into the outlet header of eitherthe primary or an intermediate section of the superheater, or aproportion of the water may be sprayed into the outlet header of one ofsaid sections and the remainder into the corresponding header or headersof the other or others of said sections. Assuming a construction inwhich water for steam temperature control purposes may be delivered intotwo or more headers of the superheater, the apparatus may be such that aproportion ofthe water will be delivered in regulated quantity into eachheader whenever the control is operating, or it may be such that toeffect a relatively small reduction in steam temperature a regulatedquantity of water may be injected into one only of said headers and whena greater desuperheating effeet is required, an appropriate amount ofwater may be delivered also into the other, or another of said headers.

It will be appreciated that Where water is sprayed into the outletheader of any section of a multi-pass superheater preceding the penutimate section, at the end of such header remote from its outlet end,said water, in addition to being thoroughly mixed with the steam in saidheader, will traverse said penultimate section, and it may be anotherintermediate section or sections of the superheater, in which only amoderate temperature is reached, and will be fully vaporised before itcan enter the elements of the final section.

An embodiment of the invention is illustrated diagrammatically in theaccompanying drawing in which I and 2 are the inlet and outlet headersof the primary section of a two-stage supersuperheated steam main orpoint of use by the,

pipe 9.

In the end of the header 2 remote from its connection with the pipe 8,i. e; remote'from its outlet end, a water injecting device H1 isarranged;

such device being fed with water by a pipe I l equipped with athermostatic valve |2,- the temperature responsive element 13controlling such valve being arranged in the path of'the steam leavingthe outlet header 4 of the final'section of the superheater-convenientlyas shown in the pipe 9 close to the said heater.

The water injecting device Ill may be a spray nozzle or nozzles of anyknown or appropriate type adapted to cause the water to issue in theform of a fine spray or mist,-or it may be of the rose type adapted todeliver a large number of fine streams. As a further alternative, thewater supply pipe H may project a short distance into the header 2 andbe finely perforated ata relatively large number of points, the end ofthe pipe being closed except for any perforations it may be desired toprovide in-the end closure.

The-manner in which the quantity of water injected into the steam willbe regulated by. the thermostatic control gear inv order to maintain thefinal steam temperature constant, or approxi- It will be appreciatedthat the streams of steam issuing from the elements 5 into the header 2set up considerable turbulence in such header, and

- that in consequence the water injected into the .water amongst theelements of the final superheater of a controlled superheatinginstallation of the type indicated, with its attendant disadvantages, isavoided in a simple, cheap and efiicient manner without the employmentof any external and relatively expensive mixing conduit or vessel.

What is claimed is:

In a superheater having elongated inlet and outlet headers withsuperheater tubes connected in parallel into openings in the side wallof said outlet header at a plurality of points spaced longitudinallythereof; an ofitake pipe for superheated steam connecting with saidoutlet header at or closely adjacent one end thereof; and means :forinjecting water into said outlet header from the end thereof remote fromsaid offtake pipe, said injecting means being positioned to introducewater in a direction axially of said header so all said water is causedto traverse with the steam a relatively long distance constituted by thelength of said header and to be met in the latter by streams of steamissuing from the elements connected thereto.

BARCLAYS BANK LIMITED, By THOMAS ERIC SONE, Manager of the ManchesterBranch, Executor John Edwin Wood, Deceased.

